Sealand 711-M28 Insanity

[JimAdkins]

Hello all, I recently purchased a used 3032 and we wanted to replace the toilet with the Sealand. I purchased it from Walmart for around $600.
https://www.walmart.com/ip/Dometic-7...Tank/976770184
We just received the toilet today, and the tank does not have a 3" outlet in the bottom like I expected. Is this something that I could add myself? If not does anyone have any recommendations on where to go to get this done?

Thanks in advance.